An In Vitro Gastrointestinal Method To Estimate Bioavailable Arsenic in Contaminated Soils and Solid Media

Abstract

A method was developed to simulate the human gastrointestinal environment and to estimate bioavailability of arsenic in contaminated soil and solid media. In this in vitro gastrointestinal (IVG) method, arsenic is sequentially extracted from contaminated soil with simulated gastric and intestinal solutions. A modified IVG-AB method, where iron hydroxide gel is used to simulate the absorption of arsenic, was also evaluated. Fifteen contaminated soils collected from mining/smelter sites ranging from 401 to 17 460 mg As kg -1 were analyzed. In vitro results were compared with in vivo relative bioavailable arsenic (RBA) determined from dosing trials using immature swine which ranged from 2.7 to 42.8% RBA. Arsenic extracted by the IVG and IVG-AB methods was not statistically different than RBA arsenic measured by the in vivo method. Arsenic extracted by the IVG stomach and intestinal phases was linearly correlated (r ) 0.83 and 0.82, respectively) with in vivo arsenic (P < 0.01). Similarly, the IVG-AB method was linearly correlated (r ) 0.79) with in vivo bioavailable arsenic (P < 0.05). All IVG methods extracted similar amounts of arsenic and provided estimates of bioavailable As in contaminated media. The IVG method may aid in the design and cost-effectiveness of remedial strategies of arsenic-contaminated sites.

The ageing effect on the bioaccessibility and fractionation of arsenic in soils from China

“…2). In agreement with other researchers (Ruby et al, 1996;Rodriguez et al, 1999;Ellickson et al, 2001), only slight differences were observed in the bioaccessibility of As between the gastric and intestinal phases for each soil (As bioaccessibility between gastric and instestinal phases significantly different (P < 0.05) for 18 out of 35 pairs). Yang et al (2002) found that DCB-extractable Fe oxide was the most important soil property controlling the initial degree of adsorption of As added to soil.…”

“…The physiologically based extraction test proposed by Ruby et al (1996) was employed with some modifications derived basically from the in vitro model proposed by Rodriguez et al (1999). Full details of the in vitro test procedure are described in Tang et al (2006); only brief details are given here.…”

“…It has been recognized that soil contaminants are usually less than 100% bioavailable (Rodriguez et al, 1999). Given the expense and time constraints associated with animal testing, much recent attention has been directed to the development of in vitro extraction tests that mimic the human digestion process.…”

Variability of arsenic bioaccessibility and metabolism in soils by human gut microbiota using different in vitro methods combined with SHIME

“…In view of the time, cost and ethical considerations associated with in vivo methods, in vitro methods are widely used in assessing human health risk. For As contaminated soils, a strong linear relationship between As relative bioavailability (RBA) and As bioaccessibility has been reported Juhasz et al, 2009Juhasz et al, , 2014Rodriguez and Basta, 1999;Ruby et al, 1996). By establishing good in vivo-in vitro correlations, these in vitro bioaccessibility methods have been proposed as surrogates to predict the RBA for refining the risk to human health of inadvertent oral soil ingestion as an important exposure route.…”

“…By establishing good in vivo-in vitro correlations, these in vitro bioaccessibility methods have been proposed as surrogates to predict the RBA for refining the risk to human health of inadvertent oral soil ingestion as an important exposure route. To date, numerous in vitro methods have been used to assess As bioaccessibility in soils (Kelly et al, 2002;Rodriguez and Basta, 1999;Ruby et al, 1996;Wragg et al, 2011). A respectable amount of information is available regarding the comparison of in vitro methods for the assessment of As bioaccessibility.…”